Providing evidence to improve practice

Individual study: Effect of marking eggs to make them unappealing to egg collectors on the nesting success of peregrine falcons Falco peregrinus and wedge-tailed eagles Aquila audax in the Flinders Ranges, South Australia

Published source details

Olsen J., Billett T. & Olsen P. (1982) A method for reducing illegal removal of eggs from raptor nests. Emu, 82


In 1979, declines were noted in the productivity of peregrine falcons Falco peregrinus and wedge-tailed eagles Aquila audax nesting in the Flinders Ranges of South Australia, which were attributed to the disappearance of eggs. On the assumption that eggs may have been illegally removed by collectors, this study investigated the effect of marking eggs in vulnerable nests, in an attempt to render them unappealing to collectors.


In addition to asking a local licensed egg collector (who agreed to co-operate) not to collect within the study area, during the 1980 breeding season, eggs in five peregrine and one wedge-tailed eagle nest were marked (using a waterproof marker pen) with a single black line around their circumference.


In 1980, 75% of marked peregrine eggs (n = 16) produced young, which was a significantly higher proportion than during 1979 (40%; n = 15 eggs), when eggs were not marked. Similarly, one of two marked eagle eggs produced young in 1980, whereas no young were produced from two unmarked eggs during 1979.

The authors acknowledge that a number of factors could have contributed to the improvement in nesting success, but note that the marking programme did not appear to have any adverse effects.


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